Earphone with noise reduction having a modified port

Abstract

An earphone is provided, the earphone being configured to provide an acoustic output signal to an ear of a wearer in dependence on an earphone audio signal and further configured to be arranged on the wearer's head in an operating position such that a front cavity between the head and the earphone is separated from ambient space. The earphone comprises a housing having a housing wall separating a rear cavity from the front cavity and from ambient space, an ear cushion, a first diaphragm suspended across an opening in the housing wall between the front cavity and the rear cavity and configured to be actively driven. The earphone further has a port structure fluidly connecting the rear cavity and ambient space through the housing wall. The port structure having a first open end fluidly coupled to the rear cavity and a second open end fluidly coupled to ambient space, and having a port cavity defined by the first open end, the second open end and a port wall, the port wall extending from the housing wall into the rear cavity and/or into the ambient space. The port wall has one or more acoustically permeable sections fluidly connecting the port cavity with the rear cavity and/or the ambient space through the port wall.

1 . An earphone configured to provide an acoustic output signal to an ear of a wearer in dependence on an earphone audio signal and further configured to be arranged on the wearer's head in an operating position such that a front cavity between the head and the earphone is separated from ambient space, the earphone comprising:
 a housing having a housing wall separating a rear cavity from the front cavity and from ambient space;   an ear cushion arranged and configured to attenuate acoustic signals entering the front cavity from ambient space when the earphone is in the operating position;   a first diaphragm suspended across an opening in the housing wall between the front cavity and the rear cavity and configured to be actively driven to provide at least a portion of the acoustic output signal;   a port structure fluidly connecting the rear cavity and ambient space through the housing wall, the port structure having a first open end fluidly coupled to the rear cavity and a second open end fluidly coupled to ambient space, and the port structure having a port cavity defined by the first open end, the second open end and a port wall, the port wall extending from the housing wall into the rear cavity and/or into the ambient space, wherein the port wall has one or more acoustically permeable sections fluidly connecting the port cavity with the rear cavity and/or the ambient space through the port wall.   
     
     
         2 . An earphone according to  claim 1 , wherein the port structure fluidly connecting the rear cavity and ambient space has a port structure resonance frequency, and wherein the port structure resonance frequency is between 100 Hz and 1 kHz, such as between 100 Hz and 500 Hz. 
     
     
         3 . An earphone according to  claim 1 , wherein the port structure and the rear cavity are configured to act as a second order low pass filter. 
     
     
         4 . An earphone according to  claim 1 , wherein the port structure is configured to act as an acoustically open hole between the rear cavity and ambient space at low frequencies. 
     
     
         5 . An earphone according to  claim 1 , wherein the one or more acoustically permeable sections are distributed along a length of the port wall, or wherein the one or more acoustically permeable sections are distributed at different distances from the housing wall. 
     
     
         6 . An earphone according to  claim 1 , wherein the port wall has a port wall area, and wherein the one or more acoustically permeable sections are distributed over between 5% and 50% of the port wall area. 
     
     
         7 . An earphone according to  claim 1 , wherein the one or more acoustically permeable sections comprises through holes, acoustically resistive openings, through holes covered with an acoustical lossy material, through holes covered with an acoustical mesh. 
     
     
         8 . An earphone according to  claim 1 , wherein the acoustic impedance of the one or more acoustically permeable sections is between 500 and 8000 L/m 2 s. 
     
     
         9 . An earphone according to  claim 1 , wherein the one or more acoustically permeable sections are distributed discretely along the length of the port wall 
     
     
         10 . An earphone according to  claim 1  any of the procoding claims, wherein the port structure has a longitudinal extension in a longitudinal direction non-parallel with the housing wall which is larger than a transversal extension in a direction parallel to the housing wall. 
     
     
         11 . An earphone according to  claim 1 , wherein the port structure comprises a tubular member having a first open end fluidly coupled to the rear cavity and a second open end fluidly coupled to ambient space, the tubular member having a tubular member wall defining the port cavity, and wherein the tubular member has a base and a height, the base having a circumscribed circle or the base being circular, wherein the height relative to a diameter of the circumscribed circle or of the circular base is larger than one. 
     
     
         12 . An earphone according to  claim 1 , wherein the one or more acoustically permeable sections are dimensioned to dampen the resonance of the port structure by at least 6 dB. 
     
     
         13 . An earphone according to  claim 1 , wherein at least one acoustically permeable section is a longitudinal section having a length corresponding to at least 80% of a length of the port wall, or wherein at least one acoustically permeable section is a circumferential section extending along at least 80% of a circumference of the port wall, and/or wherein a width of the longitudinal section and/or a width of the circumferential section corresponds to less than 25% of the length of the port wall. 
     
     
         14 . An earphone according to  claim 1 , the earphone further comprising a noise cancelling circuit being configured to receive the earphone audio signal, to implement an active noise cancelling function and to provide a noise cancelling audio signal to the ear of a wearer. 
     
     
         15 . A hearing device comprising one or two earphones according to  claim 1  and configured to provide an earphone audio signal to each of the one or two earphones in dependence on one or more audio input signals.